diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index a98a72e55d2c..e7557f6a0dc1 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -682,16 +682,10 @@ wait_mpj()
 	done
 }
 
-kill_wait()
-{
-	kill $1 > /dev/null 2>&1
-	wait $1 2>/dev/null
-}
-
 kill_events_pids()
 {
-	kill_wait $evts_ns1_pid
-	kill_wait $evts_ns2_pid
+	mptcp_lib_kill_wait $evts_ns1_pid
+	mptcp_lib_kill_wait $evts_ns2_pid
 }
 
 kill_tests_wait()
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 56cbd57abbae..e421b658d748 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -217,3 +217,12 @@ mptcp_lib_get_info_value() {
 mptcp_lib_evts_get_info() {
 	mptcp_lib_get_info_value "${1}" "^type:${3:-1}," < "${2}"
 }
+
+# $1: PID
+mptcp_lib_kill_wait() {
+	[ "${1}" -eq 0 ] && return 0
+
+	kill -SIGUSR1 "${1}" > /dev/null 2>&1
+	kill "${1}" > /dev/null 2>&1
+	wait "${1}" 2>/dev/null
+}
diff --git a/tools/testing/selftests/net/mptcp/userspace_pm.sh b/tools/testing/selftests/net/mptcp/userspace_pm.sh
index 2413059a42e5..f4e352494f05 100755
--- a/tools/testing/selftests/net/mptcp/userspace_pm.sh
+++ b/tools/testing/selftests/net/mptcp/userspace_pm.sh
@@ -108,15 +108,6 @@ test_fail()
 	mptcp_lib_result_fail "${test_name}"
 }
 
-kill_wait()
-{
-	[ $1 -eq 0 ] && return 0
-
-	kill -SIGUSR1 $1 > /dev/null 2>&1
-	kill $1 > /dev/null 2>&1
-	wait $1 2>/dev/null
-}
-
 # This function is used in the cleanup trap
 #shellcheck disable=SC2317
 cleanup()
@@ -128,7 +119,7 @@ cleanup()
 	for pid in $client4_pid $server4_pid $client6_pid $server6_pid\
 		   $server_evts_pid $client_evts_pid
 	do
-		kill_wait $pid
+		mptcp_lib_kill_wait $pid
 	done
 
 	local netns
@@ -210,7 +201,7 @@ make_connection()
 	fi
 	:>"$client_evts"
 	if [ $client_evts_pid -ne 0 ]; then
-		kill_wait $client_evts_pid
+		mptcp_lib_kill_wait $client_evts_pid
 	fi
 	ip netns exec "$ns2" ./pm_nl_ctl events >> "$client_evts" 2>&1 &
 	client_evts_pid=$!
@@ -219,7 +210,7 @@ make_connection()
 	fi
 	:>"$server_evts"
 	if [ $server_evts_pid -ne 0 ]; then
-		kill_wait $server_evts_pid
+		mptcp_lib_kill_wait $server_evts_pid
 	fi
 	ip netns exec "$ns1" ./pm_nl_ctl events >> "$server_evts" 2>&1 &
 	server_evts_pid=$!
@@ -624,7 +615,7 @@ test_subflows()
 			      "10.0.2.2" "$client4_port" "23" "$client_addr_id" "ns1" "ns2"
 
 	# Delete the listener from the client ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	local sport
 	sport=$(mptcp_lib_evts_get_info sport "$server_evts" $SUB_ESTABLISHED)
@@ -663,7 +654,7 @@ test_subflows()
 			      "$client_addr_id" "ns1" "ns2"
 
 	# Delete the listener from the client ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$server_evts" $SUB_ESTABLISHED)
 
@@ -702,7 +693,7 @@ test_subflows()
 			      "$client_addr_id" "ns1" "ns2"
 
 	# Delete the listener from the client ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$server_evts" $SUB_ESTABLISHED)
 
@@ -740,7 +731,7 @@ test_subflows()
 			      "10.0.2.1" "$app4_port" "23" "$server_addr_id" "ns2" "ns1"
 
 	# Delete the listener from the server ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$client_evts" $SUB_ESTABLISHED)
 
@@ -779,7 +770,7 @@ test_subflows()
 			      "$server_addr_id" "ns2" "ns1"
 
 	# Delete the listener from the server ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$client_evts" $SUB_ESTABLISHED)
 
@@ -816,7 +807,7 @@ test_subflows()
 			      "10.0.2.2" "10.0.2.1" "$new4_port" "23" "$server_addr_id" "ns2" "ns1"
 
 	# Delete the listener from the server ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$client_evts" $SUB_ESTABLISHED)
 
@@ -862,7 +853,7 @@ test_subflows_v4_v6_mix()
 			      "$server_addr_id" "ns2" "ns1"
 
 	# Delete the listener from the server ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sport=$(mptcp_lib_evts_get_info sport "$client_evts" $SUB_ESTABLISHED)
 
@@ -974,7 +965,7 @@ test_listener()
 	sleep 0.5
 
 	# Delete the listener from the client ns, if one was created
-	kill_wait $listener_pid
+	mptcp_lib_kill_wait $listener_pid
 
 	sleep 0.5
 	verify_listener_events $client_evts $LISTENER_CLOSED $AF_INET 10.0.2.2 $client4_port